The invention relates to a container for pasteurizing sludge, particularly sewage sludge in which the raw sludge is supplied at the necessary pasteurization temperature.
In known pasteurization systems of this type, the sludge is initially heated to the pasteurization temperature, then introduced into the pasteurization container and left to stand in the latter for approximately 30 minutes. In other known installations, the sludge is circulated through a pasteurization container and a heating station until it has reached the pasteurization temperature, after which the heated sludge is also left to stand in the pasteurization container for 30 minutes. In these known systems, the pasteurized sludge is drained off from the container at the end of the pasteurization time, when a new pasteurization cycle commences. Thus, these typical batch plants operate on a discontinuous basis.
In other known installations, attempts have been made to overcome the disadvantage of discontinuous batch operation, i.e. the batchwise or intermittent heating, pasteurization and cooling of the sludge, by providing a plurality of pasteurization containers which are charged in a time-staggered manner to obtain a quasi-continuous operation.
All of these known installations have an important disadvantage. The container in which the sludge is pasteurized is always infected at certain points and possibly everywhere, either by the infected sludge itself, or by the infected air, or by both of them, so that when the pasteurized sludge is drawn from the pasteurization container, the sludge is immediately contaminated again by the reabsorbed infected air.